1. Field of the Invention
The present invention relates to a high-speed fluidic device for pouring a fluid by high-speed rotation and particularly to a high-speed fluidic device including a high-speed fluidic machine such as a turbo machine, a supercharger or a ventilator.
2. Description of the Related Art
As a high-speed fluidic device, a supercharger for vehicle engine has been heretofore disclosed, for example, in JP-A-4-203421 and JP-A-11-294548. The supercharger is of a centrifugal type in which motive power is directly belt-transmitted from a drive shaft of an engine to a speed-increasing mechanism to increase speed to thereby drive an impeller of the speed-increasing mechanism to rotate.
In the device disclosed in JP-A-4-203421, a planetary gear mechanism is used to make the speed-increasing rate of the speed-increasing mechanism high. When the number of revolutions exceeds a value in a range of from the order of tens of thousands of rpm to the order of a hundred thousand of rpm, there is however a large problem in life as well as in vibration and noise of gears.
On the other hand, the device disclosed in JP-A-11-294548 is of a type using a planetary roller of a friction roller mechanism. The device has a structure in which pressuring force required for traction drive is obtained when the planetary roller and a sun shaft are tightened by a flexible outer ring. For this reason, slip occurs in a state of high rotational speed and high torque so that drive power cannot be transmitted to the impeller. In order to prevent this slip, the outer ring needs to tighten the planetary roller by a more intensive force. If so, efficiency is lowered because the planetary roller is pressed by an excessive pressing force in a state of low rotational speed and low torque. At the same time, there is a problem in life because an intensive pressing force always works.
As described above, in the method in which motive power is obtained by direct belt transmission from the drive shaft of the engine, the mount position of the supercharger is inevitably limited to a position on the same plane with a pulley mounted on a crankshaft of the engine.
On the other hand, an engine room is much crowded with the recent advance of functionalization of the engine, electronic application to an automobile, security safeguards against collision of a vehicle body, and so on. There is no degree of freedom for the installation position of the supercharger.
From the supercharger side, the distance to an air-intake port of the engine, the installation position of an inter-cooler, the distance to the inter-cooler, and so on, are required to be optimized.
It is however difficult to optimize these distances and installation position because the installation position of the supercharger is limited for the aforementioned reason.
In the method in which motive power is taken out from the crankshaft of the engine, the number of revolutions of a turbine in the supercharger is proportional to the number of revolutions of the engine. As a result, if the supercharger is designed so that a sufficient supercharging effect can be obtained even in the case where the engine rotates at a low speed, there is a disadvantage in that the quantity of supply air and boost pressure become too large inevitably when the engine rotates at a high speed. As a method for eliminating this disadvantage, the provision of a continuously variable transmission apparatus or an electromagnetic clutch in an input pulley portion of the speed-increasing mechanism has been proposed. In this method, there is however a problem that the system is complicated to bring increase in weight, volume and cost.
Under such circumstances, an object of the invention is to provide a high-speed fluidic device in which high transmission efficiency can be obtained as well as quiet and smooth motive power transmission can be performed and which is high both in installability and in controllability, small in size, light in weight and low in cost.
The transmission motive power of the friction roller type transmission exhibits 20 kW at maximum and about 5 kW in an ordinary state even in a light-pressure type having a supercharging pressure of about 1.5 atmospheres for 2 L engine. When an electric motor is used as a drive source on the assumption that the efficiency of the electric motor is about 90%, heat of about 2 kW is generated when the maximum transmission motive power is produced and heat of about 0.5 kW is generated when the transmission motive power is 5 kW.
As described above, the efficiency of the friction roller type transmission is high on the whole region but a loss of about 5% occurs even in the case where the efficiency is 95%. A large part of the loss makes a heat loss. This heat loss is added to a heat loss of the electric motor. Furthermore, a larger amount of heat is generated in a supercharger for large exhaust capacity engine or a supercharger high in supercharging pressure. In addition, heat is further generated by adiabatic compression when air is compressively fed to the engine by the impeller.